This invention relates to a graft/stent system for use in human or animal surgery. One example of this type of graft/stent is disclosed in EP 0326426A which describes an artificial blood vessel in the form of a tubular sheath having a ring-like member located at each of its two ends. Another example, disclosed in EP 0461791A, is an aortic graft with one of its tubular ends divided into two branches.
According to an aspect of the present invention, there is provided a tubular graft/stent as specified in claim 1.
According to another aspect of the present invention, there is provided a tubular graft/stent as specified in claim 9.
The invention proposes a medical tubular graft stent which comprises a tubular sheath having at intervals along its length a plurality of ring-like rigid members, wherein said members are attached to the sheath around their respective circumferences and are made of a shape memory material, so that when said members change shape, the sheath adopts a new cross-section in conformity with them along its whole length.
Preferably, this provides a compliant tubular sheath, into which a series of open rings are integrated. The rings act as rigidising members and are capable of being radially compressed by mechanical forces in the martensitic phase so as to reduce the diameter, and of then returning in the austenitic phase to a memorised, larger diameter by a thermal effect.
In a further aspect, the invention proposes a tubular graft comprising a tubular sheath having a branch tube which is sufficiently flexible to be inverted so as to be housed within the sheath during an insertion operation in a human or animal body, and to be redeployed as a branch after said operation. The sheath and/or the branch tube may employ annular rigid members of a shape memory material, as explained above. In all cases, the members are preferably discontinuous, e.g. a ring with a break so as to facilitate compression and re-expansion.